Vane-type hydraulic pump

ABSTRACT

A vane-type hydraulic pump is disclosed which employs a variable working chamber. It employs a by-pass regulator formed to include a flow-control valve and a pilot pressure relief valve which are formed as part of the pump shaft, thereby providing a reduction in pump size and weight.

United States Patent [1 1 V Winter May 28, 1974 1 1 VAN E-TYPE HYDRAULICPUMP [56] References Cited [75] Inventor: Klaus Winter,Ju1ius-Brecht-Str., UNITED STATES PATENTS Germany 2,899,941 8/1959 Adams417/310 x [73] Assignee: International Telephone a 3,415,194 12/1968Connelly 417/310 X Telegraph Industries, Inc., New York, NY. PrimaryExaminerCarl1on R. Croyle Assistant ExaminerRichard Sher [22] 1973Attorney, Agent, or Firm-l B. Raden; D. P. Warner [21] Appl. No.2353,228

, [57] ABSTRACT [30] Foreign Application Priority Data A vane-typehydraulic pump is disclosed which em- Apr. 21, 1972 Germany 2219587ploys a variable, jworking chamber It e lo a b I pass regulator formedto include a flow-control valve Cl 1 and a pilot pressure relief valvewhich are formed as [51] Int. Cl. F04b 23/12, F04b 39100 t f the pumpshaft, thereby providing a reduction [58] Field 01' Search; 417/310,284, 87, 302, in pump size and weight,

2 Claims, 2 Drawing Figures r l VANE-TYPE HYDRAULIC PUMP BACKGROUND OFTHE INVENTION 1. Fieldof the Invention This invention relates to avane-type hydraulic pump. An exemplary pump includes a rotor providedwith radially movable vanes which, together with the rotor, bilaterallydisposed side plates, a cam disc and a working chamber, enclose acontinuously changeing volume when the rotor is driven. By-passregulation is provided in an exemplary pump by the combination of a flowcontrol valve and a pressure relief valve formed as part of the pumpdrive shaft portion of the rotor.

2. Description of the Prior Art Previously known vane-type pumps havebeen controlled by means of a by-pass regulator. In the knownembodiments, the valve has been placed either in the housing member orin the pump housing cover with the disadvantage that special ducts andbores have had to be provided in the housing, resulting in relativelylarge overall dimensions for such pumps.

SUMMARY OF THE INVENTION It is the object of the present invention toprovide an efficient vane-type hydraulic pump of particularly lightweight and small dimensions. Furthermore, the pressure-medium connectorsshould be arranged independently of the position of the by-pass valve.

In accordance with the present invention, this is achieved in that thereis provided in a concentric bore in the pump shaft, a flow-control valveof the conventional type communicating with a pilot pressure-reliefvalve, said pump shaft being preferably provided with radial ductsconstituting the inlet and outletducts for the valves. In order toincrease pump efficiency,an annular collar is provided spaced. from thepump shaft and embracing it concentrically, one .of the ducts openingout to the annular po'rt area through which pressure medium is flowingout.

BRIEF DESCRIPTION OF THE DRAWINGS This invention allows for a largevariety of embodiments. One embodiment will be described with referenceto the attached drawing in which:

FIG. 1 is a longitudinal view of the hydraulic pump; and

FIG. 2 is a cross-sectional view of the pumpon the lines A-B accordingto FIG. I.

In essence, the pump includes the pump housing 1 comprising the suctionport 2 and the pressure port 3; the pump shaft 4 supported in thehousing I and comprising the rotor 5 and the vanes 43 (radially movablelamellae); the stationary cam disc 6; the bilaterally disposed sideplates 7, 8; and the housing cover 9 tightly sealing the pump housing 1.

The pump shaft 4 is provided with a blind bore 10 closed by means of adisc 1 I and containing a piston 13 which is movable in longitudinaldirection against the force of a pressure spring 12. The blind bore 10also contains a pressure-relief valve indicated generally by numeral 14.In addition, a plurality of radially extending ducts have been providedin the pump shaft 4, thus connecting the longitudinal bore 10 with theworking chambers filled with pressure medium and arranged radiallyoutwardly. Said ducts are: Duct 15 connecting the chamber behind thepressure-relief valve 14 with the ring duct 16 for lubricating thepump-shaft bearing 17; the radial bore 18 connecting the chamber betweenpiston 13 and relief valve 14, via duct 32 in the side plate 7, to thepressure-sided ring chamber 19; the radial duct 20 connecting the pocket21 in the side plate 8 with the blind bore 22 of piston 13; and finallythe radial duct 23 connecting the blind bore 10 of the pump shaft 4 withthe ringchamber 24 disposed between the side plate 8 and the sheet-metalcollar 35.

When the pump shaft 4 is driven, the pressure medium to be supplied willbe sucked in via the suction port 2, therefrom flowing to chamber 25provided between the housing cover 9 and the end of the pump shaft 4 orthe sheet-metal collar 35, respectively, and further through the spacebetween stud 26 and pump shaft 4 into ring chamber 24 until it reachesthe working chambers 28 of rotor 5 via an axially extending duct '27.Flow is then directed to pocket 28a and, through duct 38, to ringchamber 19 from which the pressure medium will be supplied to pressureport 3.

If a determined pressure has been built up in the ring chamber 19 or inthe pockets 28a and 21 respectively, the discharge-pressurized mediumflows also from pocket 21 through the ducts 29, 20 and 30 to the blindbore 22 of piston 13, inducing said piston to move against the force ofspring 12 in the direction of the arrow until piston 13 has reached aposition enabling part. of the supplied pressure medium to flow back tothe ring chamber 24 through the radial duct 23. Duct 23 beingcomparatively narrow, the pressure medium passes the sheet-metal collar35, 26 at high speed, thus generating a pump effect in the area of theannular port 40 for the benefit of the suction flow.

If an undesirably high pressure has been built up at the pressure port 3for the pressure line or in ring chamber 19 respectively, the pressurehead will also affect the pressure-relief valve 14 (the space betweenpiston l3 and valve .14) through the radially extending ducts 32 and 18.Under the influence of the pressure,

the ball 33 moves in opening direction, i.e. leftward, thus opening thepassage towards duct 15 or ring duct 16 respectively. From ring duct 16the pressure medium is allowed to flow back through duct 34 to thesuction-side of ring chamber 41.

The vane-type hydraulic pump described above includes both aflow-control valve 13, 30 and a pilot pressure-relief valve 14. Bothvalves are concentrically disposed in the pump shaft.

The injection effect within the area of the annular port 40 has provedto be particularly useful in that its specially designed sheet-metalcollar 35, 26, in connection with the radial duct 23, serves as an aidto improve pump performance. The guide for the bypass spring 12 iscoated with suitable plastics material (e.g. PTFE) to minimize theinfluence of friction in the event of buckling, e.g. due to centrifugalforces occurring at high rotational speed.

While the principles of the invention have been described above inconnection with specific apparatus and applications, it is to beunderstood that this de-. scription is made only by way of example andnot as a limitation on the scope of the invention.

I claim:

1. A vane-type hydraulic pump; comprising means forming a workingchamber of continuously changing volume when a rotor is driven; saidmeans including a rotor formed about a pump shaft, radially movablevanes, bilaterally disposed side plates, and a cam disc; 2. In a pump asclaimed in claim 1, an annular collar a concentric bore in the pumpshaft; and aflow-control spaced from the pump shaft and forming anannular valve and a pilot pressure-relief valve located within port areaaround said shaft, and one of the outlet ducts said bore; said pumpshaft including radial ducts constiopening out to the annular port area.

tuting inlet and outlet ducts for each of said valves. 5

1. A vane-type hydraulic pump; comprising means forming a workingchamber of continuously changing volume when a rotor is driven; saidmeans including a rotor formed about a pump shaft, radially movablevanes, bilaterally disposed side plates, and a cam disc; a concentricbore in the pump shaft; and a flow-control valve and a pilotpressure-relief valve located within said bore; said pump shaftincluding radial ducts constituting inlet and outlet ducts for each ofsaid valves.
 2. In a pump as claimed in claim 1, an annular collarspaced from the pump shaft and forming an annular port area around saidshaft, and one of the outlet ducts opening out to the annular port area.